Method and flexible lattice foams

ABSTRACT

A method of making a foamed article, for example a foamed component for an article or footwear, comprises forming a structure of interconnected, unfoamed, thermoplastic polymeric members spaced to define openings between the thermoplastic polymeric members. The structure may be made by printing a thermoplastic polymeric material with a three-dimensional printer. The thermoplastic polymeric members are heated to a first temperature to soften the thermoplastic polymeric members and the softened thermoplastic polymeric members are infused with at least one inert gas at a first pressure greater than atmospheric pressure. The first pressure is sufficient to cause the at least one inert gas to permeate into the softened thermoplastic polymeric members. After being infused with the inert gas, the pressure is reduced to at least partially foam the thermoplastic polymeric members.

This application claims priority to U.S. Provisional Application No.62/075,535, filed Nov. 5, 2014, which is incorporated herein in itsentirety by reference.

FIELD

The present disclosure relates to methods for forming flexible foams andarticles made by the methods.

INTRODUCTION

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Flexible foams are used for cushioning, support, and to absorb impacts,for example in seats and furniture, footwear, packaging, straps,protective gear, and so on. In general, foam materials are made insheets or blocks and cut to a desired pre-form shape, then finished to afinal shape.

Foamed midsoles for athletic footwear may be made from crosslinkedpoly(ethylene co-vinyl acetate) (EVA), for example, which may be cutfrom a block or sheet of foam. Injection molding may typically not beused because foam materials made by this method must have higherspecific gravities to foam uniformly.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1A and FIG. 1B are respectively side and top perspective views ofan example flexible foamed lattice;

FIG. 2 is a perspective view of an alternative example flexible foamedlattice;

FIG. 3 is a perspective view of an embodiment of a flexible foamedlattice midsole for an article of footwear; and

FIG. 4 is a perspective view of an alternative embodiment of a flexiblefoamed lattice midsole for an article of footwear

DESCRIPTION

A method of making a foamable article, for example a foamable componentfor an article or footwear, comprises forming a structure ofinterconnected thermoplastic polymeric members spaced to define openingsbetween the thermoplastic polymeric members. Each opening may have atleast one dimension that is greater than at least one dimension of atleast one adjacent unfoamed thermoplastic polymeric member. All or someof the openings may be interconnected. All or some of the openings maybe enclosed by thermoplastic members. At least a portion of theinterconnected thermoplastic polymeric members may be arranged in arepeating pattern, for example a pattern that repeats in twoperpendicular directions, for example a regular three-dimensionallattice pattern with uniform repeating units. The structure may be madeby printing a thermoplastic polymeric material with a three-dimensionalprinter in a unitary article of the interconnected thermoplasticpolymeric members. The thermoplastic polymeric material may be athermoplastic elastomer composition. The thermoplastic polymeric membersmay have a cross-sectional shape that is generally circular, oval,square, rectangular, or other polygonal shape, or that is irregularlyshaped. “Generally” is used here to indicate an overall shape that mayhave imperfections and irregularities, such as bumps, dents, and so on.The thermoplastic polymeric members are heated to a first temperaturethat is below a temperature at which the structure would collapse tosoften the thermoplastic polymeric members and then the softenedthermoplastic polymeric members are infused with at least one inert gasat a first pressure. The first pressure may be greater than atmosphericpressure. The temperature to which the thermoplastic polymeric membersare heated is sufficient to soften the thermoplastic polymeric members,but does not cause collapse of the structure of interconnectedthermoplastic polymeric members spaced to define openings between thethermoplastic polymeric members. The inert gas may be a noble gas,nitrogen, carbon dioxide, or any combination thereof. The first pressureis sufficient to cause the at least one inert gas to permeate into thesoftened thermoplastic polymeric members, forming infused softenedthermoplastic polymeric members. The amount of the at least one inertgas infused into the softened thermoplastic polymer members issufficient to produce at least partial foaming of the softenedthermoplastic polymer in a subsequent step where the infused softenedthermoplastic polymer is exposed to an atmosphere at a lower pressure.After being infused with the inert gas, the thermoplastic polymericmembers can optionally be cooled to a second temperature, and thepressure reduced to atmospheric pressure (i.e., without foaming thethermoplastic polymeric members). The foamable article may includeportions other than the thermoplastic polymeric members, which portionsmay be interior or exterior portions. An interior portion may be, forexample, an interior solid portion of regular geometric shape or ofirregular shape. An exterior portion may form at least a portion of aside or perimeter of the foamable article, which may be of uniform ornon-uniform thickness, and which may include extensions into thearticle. The portions other than the thermoplastic polymeric members canbe formed from a second thermoplastic material. The second thermoplasticmaterial can have a Vicat softening temperature above the Vicatsoftening temperature of the thermoplastic polymeric members. Theportions other than the thermoplastic polymeric members can be formed byinjection molding. Alternatively, the portions other than thethermoplastic polymeric members can be formed using vacuum and/orthermoforming techniques. The article may include a first kind ofinterconnected thermoplastic polymeric members that are softened andinfused with the at least one inert gas and a second kind ofinterconnected thermoplastic polymeric members that are not softenedand/or are not infused during the step of heating and infusing of thefirst kind of interconnected thermoplastic polymeric members.

The foamable article, for example a foamable component for an article orfootwear, can be again heated to a temperature at which thethermoplastic polymeric members soften to at least partially foam thethermoplastic polymeric members. The foamable article can be heated tothe temperature at which the thermoplastic polymeric members softenunder pressure (for example at a pressure greater than atmosphericpressure) and foamed with a reduction of the pressure, for example areduction to atmospheric pressure.

A method of making a foamed article, for example a foamed component foran article or footwear, comprises heating interconnected, unfoamed,thermoplastic polymeric members of the article that are infused with atleast one inert gas to soften the thermoplastic polymeric members. Thethermoplastic polymeric material may be a thermoplastic elastomercomposition. The thermoplastic polymeric members may be infused withinert gas below or up to a saturation point. In other words, thethermoplastic polymeric members may be infused with the inert gas at aconcentration below the saturation point, or at the saturation point.The interconnected, unfoamed, thermoplastic polymeric members are heatedto a first temperature that is below a temperature at which thestructure would collapse to soften the thermoplastic polymeric membersand allow the thermoplastic polymeric members to at least partiallyfoam. The unfoamed, thermoplastic polymeric members are spaced to defineopenings between the unfoamed, thermoplastic polymeric members. Eachopening may have at least one dimension that is greater than at leastone dimension of at least one adjacent unfoamed thermoplastic polymericmember. All or some of the openings may be interconnected. All or someof the openings may be enclosed by thermoplastic members. After thethermoplastic polymeric members at least partially foam, openings mayremain between a portion of, or all of, the thermoplastic polymericmembers. At least a portion of the interconnected thermoplasticpolymeric members may be arranged in a repeating pattern, for example apattern that repeats in two perpendicular directions, or example aregular three-dimensional lattice pattern with uniform repeating units.The thermoplastic polymeric members may have a cross-sectional shapethat is circular, oval, square, rectangular, or other polygonal shape,or that is irregularly shaped. The inert gas may be a noble gas,nitrogen, carbon dioxide, or any combination thereof. The thermoplasticpolymeric members may be heated to the first temperature at a firstpressure, then the pressure may be reduced to a second pressure lessthan the first pressure to allow the thermoplastic polymeric members toat least partially foam. The first pressure may be greater thanatmospheric pressure.

A method of making a closed-cell foamed article, for example a foamedcomponent for an article or footwear, comprises forming a structure ofinterconnected, unfoamed, thermoplastic polymeric members spaced todefine openings between the thermoplastic polymeric members. Eachopening may have at least one dimension that is greater than at leastone dimension of at least one adjacent unfoamed thermoplastic polymericmember. All or some of the openings may be interconnected. All or someof the openings may be enclosed by thermoplastic members. At least aportion of the interconnected thermoplastic polymeric members may bearranged in a repeating pattern, for example a pattern that repeats intwo perpendicular directions, for example a regular three-dimensionallattice pattern with uniform repeating units. The structure may be madeby printing a thermoplastic polymeric material with a three-dimensionalprinter in a unitary article of the interconnected thermoplasticpolymeric members. The thermoplastic polymeric material may be athermoplastic elastomer composition. The thermoplastic polymeric membersmay have a cross-sectional shape that is circular, oval, square,rectangular, or other polygonal shape, or that is irregularly shaped. Ina first location, the thermoplastic polymeric members are heated to afirst temperature below a temperature at which the structure collapsesto soften the thermoplastic polymeric members and the softenedthermoplastic polymeric members are infused with at least one inert gasat a first pressure. The inert gas may be a noble gas, nitrogen, carbondioxide, or any combination thereof. The amount of inert gas infusedinto the thermoplastic polymeric members may be below or up to asaturation point. The first pressure is sufficient to cause the at leastone inert gas to permeate into the softened thermoplastic polymericmembers. The first pressure can be greater than atmospheric pressure.After being infused with the inert gas, the thermoplastic polymericmembers are cooled to a second temperature, and the pressure is reduced,for example, to atmospheric pressure. The cooled structure istransferred to a second location; and the thermoplastic polymericmembers are heated to a third temperature below a temperature at whichthe structure collapses to soften the thermoplastic polymeric membersand at least partially foam the thermoplastic polymeric members. Duringthis step, the pressure is a pressure at which the infused inert gaswill partition out of the softened thermoplastic members, causing thesoftened thermoplastic to foam. The second location may be a mold. Thesecond location may be remote, such as a location in a differentbuilding from a building in which the article is infused with the atleast one inert gas. The third temperature may be the same as ordifferent from the first temperature. The thermoplastic polymericmembers may be heated to the third temperature at a second pressuregreater than atmospheric pressure, then the pressure may be reduced to athird pressure less than the second pressure to allow the thermoplasticpolymeric members to at least partially foam.

A method of making a closed-cell foamed article, for example a foamedcomponent for an article or footwear, comprises forming a structurecomprising interconnected, unfoamed, thermoplastic polymeric membersspaced to define openings between the thermoplastic polymeric members.Each opening may have at least one dimension that is greater than atleast one dimension of at least one adjacent unfoamed thermoplasticpolymeric member. All or some of the openings may be interconnected. Allor some of the openings may be enclosed by thermoplastic members. Atleast a portion of the interconnected thermoplastic polymeric membersmay be arranged in a repeating pattern, for example a pattern thatrepeats in two perpendicular directions, for example a regularthree-dimensional lattice pattern with uniform repeating units. Thestructure may be made by printing a thermoplastic polymeric materialwith a three-dimensional printer as an article of the interconnectedthermoplastic polymeric members. The thermoplastic polymeric materialmay be a thermoplastic elastomer composition. The thermoplasticpolymeric members may have a cross-sectional shape that is circular,oval, square, rectangular, or other polygonal shape, or that isirregularly shaped. The foamable article may include portions other thanthe thermoplastic polymeric members, which portions may be interior orexterior portions. An interior portion may be, for example, an interiorsolid portion of regular geometric shape or of irregular shape. Anexterior portion may form at least a portion of a side or perimeter ofthe article, which may be of uniform or non-uniform thickness, and whichmay include extensions into the article. The article may include a firstkind of interconnected thermoplastic polymeric members that are softenedand infused with the at least one inert gas and a second kind ofinterconnected thermoplastic polymeric members that are not softenedand/or infused with the at least one inert gas under the conditions atwhich the first kind of interconnected thermoplastic polymeric membersare softened and infused. These features may be included in the articleby using more than one material in printing the article bythree-dimensional printing. The thermoplastic polymeric members areheated to a first temperature below a temperature at which the structurecollapses to soften the thermoplastic polymeric members and the softenedthermoplastic polymeric members are infused with at least one inert gasat a first pressure greater than atmospheric pressure. The inert gas maybe a noble gas, nitrogen, carbon dioxide, or any combination thereof.The amount of inert gas infused into the thermoplastic polymeric membersmay be below or up to a saturation point. The first pressure issufficient to cause the at least one inert gas to permeate into thesoftened thermoplastic polymeric members. The pressure is reduced tosecond pressure below the first pressure while the first polymeric resinis or remains at or below a temperature at which the structure collapsesand at which the thermoplastic polymeric members are softened to atleast partially foam the thermoplastic polymeric members.

The article with the at least partially foamed, thermoplastic polymericmembers may be subjected to a second foaming step by heating the atleast partially foamed, thermoplastic polymeric members to a secondtemperature at or below a temperature at which the structure collapsesto soften the thermoplastic polymeric members and infusing the softenedthermoplastic polymeric members with at least one inert gas at a thirdpressure that is sufficient to cause the at least one inert gas topermeate into the softened thermoplastic polymeric members, and thenreducing the pressure to fourth pressure below the second pressure whilethe first polymeric resin is or remains at or below a temperature atwhich the structure collapses to further foam the thermoplasticpolymeric members. The third pressure may be greater than atmosphericpressure. The second temperature may be the same as or different fromthe first temperature. The at least one inert gas used in the secondfoaming step may be the same as or different from the inert gas used inthe original foaming step. Suitable examples of the inert gas are againnoble gasses, nitrogen, carbon dioxide, or any combination of these. Theamount of inert gas infused into the thermoplastic polymeric members maybe below or up to a saturation point. The third pressure is sufficientto cause the at least one inert gas to permeate into the softenedthermoplastic polymeric members and can be the same as or different fromthe first pressure. The pressure is reduced to fourth pressure below thefirst pressure while the first polymeric resin is or remains at or belowa temperature at which the structure collapses to further foam thethermoplastic polymeric members. The fourth pressure can be the same asor different from the second pressure. The second foaming step canproduce a foamed article of a lower density. The second foaming step mayalso be used for further shaping the foamed article, for example whenthe second foaming step is carried out in a mold or with a partial mold.

The disclosed methods allow a foamed article of a desired shape to bemade without cutting the shape from a block or tooling for injectionmolding a shaped foam. The disclosed methods also allow a foamed articleof a desired shape to be made without using a process which requiresremoving material, either in foamed or pre-foamed form, in order tocreate a structure of interconnected foamed members spaced to defineopenings therebetween. Three-dimensional printing of the thermoplasticpolymeric members in their desired configuration eliminates the need tocreate tooling and avoids waste generated by cutting and trimming foamsheets or blocks into a desired shape. Three-dimensional printing of thethermoplastic polymeric members permits shapes with thermoplasticpolymeric members spaced in three-dimensions that could not be injectionmolded or easily cut from a block of foam. The thermoplastic polymericmembers of the disclosed methods can be selected to have dimensions thatfacilitate adsorption of the inert gas and provide desired cushioning,support, and impact resistance. Further shaping of the foamed articlecan be carried out with relatively simple molds or partial molds.

When the structure is heated the temperatures to soften thethermoplastic polymeric members to infuse them with the at least oneinert gas or to cause the infused polymeric members to foam, thestructure should not collapse. The structure is considered to havecollapsed if the total combined volume of its openings decreases morethan 50% as a result of deformation of its polymeric members from theheat. It is desirable for the total combined volume of openings of thestructure to decrease by not more than 20% or by not more than 10% or bynot more than 5% or by not more than 1% or not to decrease by anynoticeable amount (substantially 0%).

In any of these methods, after the thermoplastic polymeric members atleast partially foam, openings may remain between a portion or all ofthe thermoplastic polymeric members. The foamed article may includeportions other than the thermoplastic polymeric members, which portionsmay be interior or exterior portions. An interior portion may be, forexample, an interior solid portion of regular geometric shape or ofirregular shape. An exterior portion may form at least a portion of aside or perimeter of the foamable article, which may be of uniform ornon-uniform thickness, and which may include extensions into thearticle. The article may include a first kind of interconnectedthermoplastic polymeric members that are softened and infused with theat least one inert gas and a second kind of interconnected thermoplasticpolymeric members that are not infused with the at least one inert gas.The foamed article may be a midsole or midsole pre-form for an articleof footwear. The foamed article may be incorporated as cushioning intoother articles. As nonlimiting examples, the foamed article may be afoamed element in footwear, such as a part of a footwear upper, such asa foamed element in a collar, a midsole or a part of a midsole, or anoutsole or a part of an outsole; foam padding in shinguards, shoulderpads, chest protectors, masks, helmets or other headgear, kneeprotectors, and other protective equipment; an element placed in anarticle of clothing between textile layers; or may be used for otherknown padding applications for protection or comfort, such as for apillow, cushion, or in an article or furniture. In various embodiments,the molded article is a midsole for an article of footwear. A midsoleprovides cushioning in the footwear. A midsole should be durable butalso preferably adds as little weight as possible to the footwear whilestill cushioning to the desired degree. A midsole also should be able tobe bonded to an outsole, an upper, or any other components (e.g., ashank, an airbag, or decorative components) in making an article offootwear.

As used in this description, “a,” “an,” “the,” “at least one,” and “oneor more” indicate interchangeably that at least one of the item ispresent; a plurality of such items may be present unless the contextunequivocally indicates otherwise. All numerical values of parameters(e.g., of quantities or conditions) in this specification, including theappended claims, are to be understood as being modified in all instancesby the term “about” whether or not “about” actually appears before thenumerical value. “About” indicates that the stated numerical valueallows some slight imprecision (with some approach to exactness in thevalue; approximately or reasonably close to the value; nearly). If theimprecision provided by “about” is not otherwise understood in thetechnological field with this ordinary meaning, then “about” as usedherein indicates at least variations that may arise from ordinarymethods of measuring and using such parameters. In addition, disclosureof ranges are to be understood as specifically disclosing all values andfurther divided ranges within the range. The terms “comprising,”“including,” and “having” are inclusive and therefore specify thepresence of stated features, steps, operations, elements, or components,but do not preclude the presence or addition of one or more otherfeatures, steps, operations, elements, or components. Orders of steps,processes, and operations may be altered when possible, and additionalor alternative steps may be employed. As used in this specification, theterm “or” includes any one and all combinations of the associated listeditems.

FIGS. 1A and 1B illustrate a first example of a foamed article 1 made bythe disclosed methods. Foamed article has a generally cylindrical shapewith an outer surface 4 and inner surface 6. The foamed article 1 isformed of interconnected thermoplastic polymeric members 10 of varyingsizes that define a plurality of openings 12 therebetween. Topperspective view 1B shows that some openings 12 may extend directly fromouter surface 4 to inner surface 6 while interconnected thermoplasticpolymeric members 10 within the article pass through or block otheropenings. In article 1, the shapes and patterns of the interconnectedthermoplastic polymeric members 10 are irregular in all threedimensions, although together they form a generally cylindrical articleof generally uniform thickness.

FIG. 2 is an example of another article made of foamed interconnectedthermoplastic polymeric members. In article 2, foamed interconnectedthermoplastic polymeric members 20 are arranged in pentagonal shapeswith pentagonal openings 22. Moving from the outermost pentagons in, thefoamed interconnected thermoplastic polymeric members 20 become thinnerand shorter to form smaller and smaller pentagons. Openings 22 are notlined up from one side of article 2 to an opposite side, but rather apath through the article 2 is tortuous.

FIG. 3 is an example of a foamed midsole 3 for an article of footwearmade of a structure of interconnected thermoplastic polymeric members 30spaced to define openings 32 between the thermoplastic polymeric members30. The thermoplastic polymeric members 30 and openings 32 are arrangedgenerally similarly to those in FIGS. 1A and 1B, as could be obtained bythree-dimensional printing of the structure of FIGS. 1A and 1B in a flatshape instead of in a cylindrical shape. In the foamed midsole 3, thereare openings 32 in side surface 36 as well as in top surface 34.Openings 32 may be generally perpendicular, generally parallel, or inanother, random direction relative to top surface 34. As shown, openings32 may be randomly interrupted by thermoplastic polymeric members 30underlying the top layer of thermoplastic polymeric members 30 formingtop surface 34.

FIG. 4 is a second example of a foamed midsole 4 for an article offootwear made of a structure of interconnected thermoplastic polymericmembers spaced to define openings between the thermoplastic polymericmembers. Foamed midsole 4 is formed of a heel section 41, midfootsection 42, and forefoot section 43. Heel section 41 and forefootsection 43 are formed of articles 1 as shown in FIGS. 1A, 1B. In heelsection 4, articles 1 are arranged in a single, side-by-side layer,while in forefoot section 43 articles 1 are arranged end-to-end inside-by-side rows 45. Although shown as a combination of articles 1,heel section 41 and forefoot section 43 can be formed as an integralstructure by three-dimensional printing. Similarly, three-dimensionalprinting of a structure of interconnected thermoplastic polymericmembers can be used to form one or more portions of a midsole structure,such as, for example, heel sections, forefoot sections, midfootsections, etc. Midfoot section 42 comprises foamed interconnectedthermoplastic polymeric members 44 spaced to define hexagonal openings.Interconnected thermoplastic polymeric members 44 are printed in offsetlayers parallel to a major face of midsole 4 with connectingthermoplastic polymeric members 44 between the layers. Heel section 41,midfoot section 42, and forefoot section 43 can be made bythree-dimensional printing as an integral article of the threestructures of sections 41, 42, and 43.

A structure of interconnected thermoplastic polymeric members spaced todefine openings between the thermoplastic polymeric members can beformed by three-dimensional printing a thermoplastic polymericcomposition. A thermoplastic polymeric composition, which may include athermoplastic elastomer, and which is suitable for foaming with at leastone inert gas, can be extruded into a length (a “filament”) having anappropriate cross-section for processing through a three-dimensionalfabricator. The three-dimensional fabricator deposits a melt of thethermoplastic polymeric composition in a pre-determined pattern onto asurface in a process that is also known as three-dimensional printing.The process is described in detail in a number of publications, forexample in US Patent Application Publication No. 2012/0241993, which isincorporated herein by reference. Three-dimensional fabrication orprinting equipment is available commercially, for example from MakerBotunder the tradename REPLICATOR.

The thermoplastic polymeric composition can include any thermoplasticpolymer, including thermoplastic elastomers that are suitable for theintended use of the foamed article to be made. Nonlimiting examples ofsuitable thermoplastic polymers and elastomers include thermoplasticpolyurethane elastomers, thermoplastic polyurea elastomers,thermoplastic polyamide elastomers (PEBA or polyether block polyamides),thermoplastic polyester elastomers, metallocene-catalyzed blockcopolymers of ethylene and α-olefins having 4 to about 8 carbon atoms,and styrene block copolymer elastomers such aspoly(styrene-butadiene-styrene),poly(styrene-ethylene-co-butylene-styrene), andpoly(styrene-isoprene-styrene).

Thermoplastic polyurethane elastomers may be selected from thermoplasticpolyester-polyurethanes, polyether-polyurethanes, andpolycarbonate-polyurethanes, including, without limitation,polyurethanes polymerized using as polymeric diol reactants polyethersand polyesters including polycaprolactone polyesters. These polymericdiol-based polyurethanes are prepared by reaction of a polymeric diol(polyester diol, polyether diol, polycaprolactone diol,polytetrahydrofuran diol, or polycarbonate diol), one or morepolyisocyanates, and, optionally, one or more chain extension compounds.Preferably the polymeric diol-based polyurethane is substantially linear(i.e., substantially all of the reactants are difunctional).Diisocyanates used in making the polyurethane elastomers may be aromaticor aliphatic, and examples include, without limitation, isophoronediisocyanate (IPDI), methylene bis-4-cyclohexyl isocyanate (H₁₂MDI),cyclohexyl diisocyanate (CHDI), m-tetramethyl xylene diisocyanate(m-TMXDI), p-tetramethyl xylene diisocyanate (p-TMXDI), 4,4′-methylenediphenyl diisocyanate (MDI, also known as 4,4′-diphenylmethanediisocyanate), 2,4- or 2,6-toluene diisocyanate (TDI), ethylenediisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane,1,6-diisocyanatohexane (hexamethylene diisocyanate or HDI), 1,4-butylenediisocyanate, and the like, which may be used in combinations. Chainextension compounds, or extenders, have two functional groups reactivewith isocyanate groups, for example, diols, dithiols, diamines, orcompounds having a mixture of hydroxyl, thiol, and amine groups, such asalkanolamines, aminoalkyl mercaptans, and hydroxyalkyl mercaptans, amongothers. The molecular weight of the chain extenders may range from about60 to about 400. Alcohols and amines are typically used. Examples ofuseful diols include ethylene glycol and lower oligomers of ethyleneglycol including diethylene glycol, triethylene glycol and tetraethyleneglycol; propylene glycol and lower oligomers of propylene glycolincluding dipropylene glycol, tripropylene glycol and tetrapropyleneglycol; cyclohexanedimethanol, 1,6-hexanediol, 2-ethyl-1,6-hexanediol,1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,3-propanediol,butylene glycol, neopentyl glycol, and combinations of these. Suitablediamine extenders include, without limitation, ethylene diamine,diethylene triamine, triethylene tetraamine, and combinations of these.Other typical chain extenders are amino alcohols such as ethanolamine,propanolamine, butanolamine, and combinations of these.

The polyester diols used in forming a thermoplastic polyurethaneelastomer are in general prepared by the condensation polymerization ofone or more polyacid compounds and one or more polyol compounds.Preferably, the polyacid compounds and polyol compounds aredi-functional, i.e., diacid compounds and diols are used to preparesubstantially linear polyester diols, although minor amounts ofmono-functional, tri-functional, and higher functionality materials(perhaps up to 5 mole percent) can be included to provide a slightlybranched, but uncrosslinked polyester polyol component. Suitabledicarboxylic acids include, without limitation, glutaric acid, succinicacid, malonic acid, oxalic acid, phthalic acid, hexahydrophthalic acid,adipic acid, maleic acid, suberic acid, azelaic acid, dodecanedioicacid, their anhydrides and polymerizable esters (e.g., methyl esters)and acid halides (e.g., acid chlorides), and mixtures of these. Suitablepolyols include those already mentioned, especially the diols. Inpreferred embodiments, the carboxylic acid component includes one ormore of adipic acid, suberic acid, azelaic acid, phthalic acid,dodecanedioic acid, or maleic acid (or the anhydrides or polymerizableesters of these) and the diol component includes one or more of includes1,4-butanediol, 1,6-hexanediol, 2,3-butanediol, or diethylene glycol.Typical catalysts for the esterification polymerization are protonicacids, Lewis acids, titanium alkoxides, and dialkyltin oxides.Polylactones, such as polycaprolactone diol, may also be used.

A polymeric polyether may be obtained by reacting a diol initiator,e.g., 1,3-propanediol or ethylene or propylene glycol, with alkyleneoxide chain-extension reagent. Polyethylene oxide (also calledpolyethylene glycol), polypropylene oxide (also called polypropyleneglycol), and block polyethylene oxide-polypropylene oxide copolymers maybe used. Two or more different alkylene oxide monomers may be randomlycopolymerized by coincidental addition or polymerized in blocks bysequential addition. Tetrahydrofuran may be polymerized by a cationicring-opening reaction initiated by formation of a tertiary oxonium ion.Polytetrahydrofuran is also known as polytetramethylene ether glycol(PTMEG).

Aliphatic polycarbonate diols that may be used in making a thermoplasticpolyurethane elastomer are prepared by the reaction of diols withdialkyl carbonates (such as diethyl carbonate), diphenyl carbonate, ordioxolanones (such as cyclic carbonates having five- and six-memberrings) in the presence of catalysts like alkali metal, tin catalysts, ortitanium compounds. Useful diols include, without limitation, any ofthose already mentioned. Aromatic polycarbonates are usually preparedfrom reaction of bisphenols, e.g., bisphenol A, with phosgene ordiphenyl carbonate.

The polymeric diol preferably has a weight average molecular weight ofat least about 500, more preferably at least about 1000, and even morepreferably at least about 1800 and a weight average molecular weight ofup to about 10,000, but polymeric diols having weight average molecularweights of up to about 5000, especially up to about 4000, may also bepreferred. The polymeric diol advantageously has a weight averagemolecular weight in the range from about 500 to about 10,000, preferablyfrom about 1000 to about 5000, and more preferably from about 1500 toabout 4000. The weight average molecular weights may be determined byASTM D-4274. The polymeric diol segments typically are from about 35% toabout 65% by weight of the polyurethane polymer, and preferably fromabout 35% to about 50% by weight of the polyurethane polymer.

Suitable thermoplastic polyurea elastomers may be prepared by reactionof one or more polymeric diamines with one or more of thepolyisocyanates already mentioned and one or more of the diamineextenders already mentioned. Polymeric diamines include polyoxyethylenediamines, polyoxypropylene diamines, poly(oxyethylene-oxypropylene)diamines, and poly(tetramethylene ether) diamines.

Suitable thermoplastic polyamide elastomers may be obtained by: (1)polycondensation of (a) a dicarboxylic acid, such as oxalic acid, adipicacid, sebacic acid, terephthalic acid, isophthalic acid,1,4-cyclohexanedicarboxylic acid, or any of the other dicarboxylic acidsalready mentioned with (b) a diamine, such as ethylenediamine,tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, ordecamethylenediamine, 1,4-cyclohexanediamine, m-xylylenediamine, or anyof the other diamines already mentioned; (2) a ring-openingpolymerization of a cyclic lactam, such as ε-caprolactam orω-laurolactam; (3) polycondensation of an aminocarboxylic acid, such as6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, or12-aminododecanoic acid; or (4) copolymerization of a cyclic lactam witha dicarboxylic acid and a diamine to prepare a carboxylicacid-functional polyamide block, followed by reaction with a polymericether diol (polyoxyalkylene glycol) such as any of those alreadymentioned. Polymerization may be carried out, for example, attemperatures of from about 180° C. to about 300° C. Specific examples ofsuitable polyamide blocks include NYLON 6, NYLON 66, NYLON 610, NYLON11, NYLON 12, copolymerized NYLON, NYLON MXD6, and NYLON 46.

Thermoplastic polyester elastomers have blocks of monomer units with lowchain length that form the crystalline regions and blocks of softeningsegments with monomer units having relatively higher chain lengths.Thermoplastic polyester elastomers are commercially available under thetradename HYTREL from DuPont.

Metallocene-catalyzed block copolymers of ethylene and α-olefins having4 to about 8 carbon atoms are prepared by single-site metallocenecatalysis of ethylene with a softening comonomer such as hexane-1 oroctene-1, for example in a high pressure process in the presence of acatalyst system comprising a cyclopentadienyl-transition metal compoundand an alumoxane. Octene-1 is a preferred comonomer to use. Thesematerials are commercially available from ExxonMobil under the tradenameExact™ and from the Dow Chemical Company under the tradename Engage™.

Styrene block copolymer elastomers such aspoly(styrene-butadiene-styrene),poly(styrene-ethylene-co-butylene-styrene), andpoly(styrene-isoprene-styrene) may be prepared may anionicpolymerization in which the polymer segments are produced sequentially,first by reaction of an alkyl-lithium initiator with styrene, thencontinuing polymerization by adding the alkene monomer, then completingpolymerization by again adding styrene. S-EB-S and S-EP-S blockcopolymers are produced by hydrogenation of S-B-S and S-I-S blockcopolymers, respectively.

The thermoplastic polymeric composition may be formed bythree-dimensional printing into an article including a structure ofinterconnected thermoplastic polymeric members spaced to define openingsbetween them. Each opening may be from about 0.5 mm or from about 1 mmor from about 2 mm to about 5 mm or to about 8 mm or to about 10 mm ineach of its dimensions. The size of the openings can range from 0.5 mmto 10 mm. The size of the openings can range from 1 mm to 10 mm. Thesize of the openings can range from 1 mm to 8 mm. The size of theopenings can range from 2 mm to 5 mm. Each opening may have at least onedimension that is greater than at least one dimension of at least oneadjacent unfoamed thermoplastic polymeric member. For example, when thethermoplastic polymeric members have a circular circumference, theadjacent openings may have at least one dimension that is greater thanthe diameter of a cross-section. In another example, a pattern in whichthe members have thin rectangular shapes, the spaces may have a smallestdimension that is greater than the thickness of the adjacentthermoplastic polymeric members. The openings may be generally elongatedin shape, and may be joined in a generally continuous path betweenopenings in different or opposite faces or surfaces of the article. Eachface of the article may have a plurality of openings, which may begenerally regularly spaced from one another. Opposite faces may haveopenings arranged in a same pattern.

The sizes of the openings defined by the interconnected, thermoplasticpolymeric members are reduced during the foaming process. In oneexample, the foamed thermoplastic polymeric members may foam to a sizewhere some or all are adjacent to other foamed thermoplastic polymericmembers. In another example, spaces remain between the thermoplasticpolymeric members after foaming.

For example, the thermoplastic polymeric members may be arranged in apattern which repeats in two directions perpendicular to one another.The pattern may have at least three repeating units in sequence in atleast one direction. The repeating units may be uniform, for examplecubes or other geometric shapes that are of a same size, or therepeating units may vary in a regular or irregular pattern. As anexample of a varying pattern, a circular pattern may expand from acenter in a plane or in three-dimensions.

The article including the structure of interconnected thermoplasticpolymeric members is made foamable by heating the thermoplasticpolymeric members to a first temperature that is below a temperature atwhich the structure collapses to soften the thermoplastic polymericmembers and infusing the softened thermoplastic polymeric members withat least one inert gas at a first pressure greater than atmosphericpressure that is sufficient to cause the at least one inert gas topermeate into the softened thermoplastic polymeric members. The inertgas may be a noble gas, nitrogen, carbon dioxide, or any combination ofthese. The first pressure is sufficient to cause the at least one inertgas to permeate into the softened thermoplastic polymeric members. Thefirst exposure is at a pressure and for a duration of time sufficientfor an amount of the gas to permeate into the softened polymer to causeat least partial foaming when the pressure is reduced. The amount of gasrequired may depend upon factors such as the surface area of thestructure, the type of polymer, the pressure, and the temperature. Theinfusing step may be continued until the point of saturation of thethermoplastic polymeric members with the gas.

The article having the thermoplastic polymeric members infused with theinert gas may then be cooled to a second temperature. The secondtemperature is one at which the gas with not significantly foam thethermoplastic polymeric members in a desired length of time. Forexample, the second temperature may be at or below about 30° C. Then,the pressure may be reduced to atmospheric pressure. The article then isa foamable article. The article can be removed from the pressure vesseland transferred to another location, for example to a mold in the samebuilding or manufacturing site or transferred to a remote site, beforeit is foamed. The article is then foamed by heating the thermoplasticpolymeric members to a second temperature that is at or below atemperature at which the structure collapses to soften the thermoplasticpolymeric members to cause the thermoplastic polymeric members to atleast partially foam the thermoplastic polymeric members. The secondtemperature may be the same as or different from the first temperatureat which the thermoplastic polymeric members were infused with the inertgas. Once the second temperature is reached, the pressure is reduced toa second pressure or released (returned to atmospheric temperature) tocause the thermoplastic polymeric members to foam.

The article having the thermoplastic polymeric members infused with theinert gas may instead be foamed immediately without interim cooling ormoving or transferring to a different position, piece of equipment,location, or geographic site. Once the softened thermoplastic polymericmembers have been infused with the at least one inert gas, the pressureto second pressure below the first pressure while the first polymericresin is below a temperature at which the structure would collapse to atleast partially foam the thermoplastic polymeric members. Thethermoplastic polymeric members remain softened while foaming. Forexample, the second pressure may be atmospheric pressure.

When the structure is foaming, expansion of the structure in one or morebut less than all directions may be constrained, for example by placingthe article with the structure of thermoplastic polymeric membersadjacent to or in direct contact with an unyielding surface. The foamingstructure may partially conform to the unyielding surface as it pressesduring foaming against the surface, expanding in unconstraineddirections.

The foamable thermoplastic polymeric members may be foamed a second timeby repeating the process. The at least partially foamed, thermoplasticpolymeric members are heated to a second temperature below a temperatureat which the structure collapses to soften the thermoplastic polymericmembers and the softened thermoplastic polymeric members are againinfused with at least one inert gas at a third pressure that issufficient to cause the at least one inert gas to permeate into thesoftened thermoplastic polymeric members, then the pressure is reducedto a fourth pressure below the third pressure while the thermoplasticpolymeric members are softened to further foam the thermoplasticpolymeric members. The third pressure may be greater than atmosphericpressure. The second temperature may be the same as or different fromthe first temperature at which the thermoplastic polymeric members weresoftened and infused during the original foaming process. The inert gasused in the second foaming process may be the same as or different fromthe inert gas used to originally at least partially foam thethermoplastic polymeric members. Thus, the inert gas may be a noble gas,nitrogen, carbon dioxide, or any combination of these. The amount ofinert gas infused into the thermoplastic polymeric members may be up toa saturation point. The third pressure may be the same as or differentfrom the first pressure used in the original infusing step process, solong as it is sufficient to cause the at least one inert gas to permeateinto the softened thermoplastic polymeric members. The pressure can bereduced to a fourth pressure while the thermoplastic polymeric membersare softened to allow the thermoplastic polymeric members to furtherfoam. The fourth pressure may be atmospheric pressure.

The article may include a structural portion other than thethermoplastic polymeric members infused with the at least one inert gasand subsequently foamed. The structural portion may be polymeric ornonpolymeric. If the structural portion is polymeric, either thestructural portion does not soften when exposed to the first temperatureand pressure, does not soften when exposed to the second temperature andpressure, or else does not foam when exposed to the secondtemperature/pressure. The structural portion may be in the form of asolid internal or surface portion of the article or may be a second setof thermoplastic polymeric members. An internal structural portion maybe, for example, a single solid portion. An exterior structural portionmay be, for example, a solid outer member forming a face of the article.

The article may include a second portion other than the thermoplasticpolymeric members infused with the at least one inert gas andsubsequently foamed. The second portion may or may not provide anystructural support to the thermoplastic polymeric members. The secondportion may be polymeric or nonpolymeric. If the second portion ispolymeric, the second portion may soften when exposed to the firsttemperature and pressure, or may soften when exposed to the secondtemperature and pressure, may foam when exposed to the secondtemperature/pressure, or any combination thereof. The second portion maybe in the form of a solid internal or surface portion of the article ormay be a second set of thermoplastic polymeric members. An internalsecond portion may be, for example, a single solid second portion. Anexterior second portion may be, for example, a solid outer memberforming a face of the article.

The closed-cell foamed article has a top outer surface, an oppositebottom outer surface, and at least one side outer surface having acommon edge with at least one of the top outer surface and the bottomsurface, wherein the side outer surface if free of openings.

Among the foamed articles that may be made in this way are footwearuppers, footwear collars, footwear tongues, footwear insoles, footwearmidsoles, shinguards, shoulder pads, chest protectors, masks, helmets,headgear, knee protectors, articles of clothing, straps; furniturecushions, and bicycle seats.

In various embodiments, the foamed articles prepared by the disclosedmethod are further molded or shaped. The foamed articles may be used asinserts in a further molding process, such as in a thermoformingprocess, or may be attached by adhesives, fasteners, thermally welded,or otherwise to further articles.

The foregoing description of particular embodiments illustrate featuresof the invention, but the invention is not limited to any of thespecific embodiments that have been described. The features describedfor particular embodiments are interchangeable and can be used together,even if not specifically shown or described. The same may also be variedin many ways. The invention broadly includes such variations andmodifications.

What is claimed is:
 1. A method of making a closed-cell foamed article,comprising a) forming a structure comprising interconnected, unfoamed,thermoplastic polymeric members spaced to define openings therebetweenby arranging at least a portion of the thermoplastic polymeric membersin a repeating pattern, the thermoplastic polymeric members comprising athermoplastic polymeric composition deposited using a three-dimensionalprinting process to form the interconnected, unfoamed, thermoplasticpolymeric members; b) heating the thermoplastic polymeric members to afirst temperature to soften the thermoplastic polymeric members, thefirst temperature being below a temperature that causes collapse of thestructure, and infusing the softened thermoplastic polymeric memberswith at least one inert gas at a first pressure greater than atmosphericpressure to cause the at least one inert gas to permeate into thesoftened thermoplastic polymeric members; c) reducing the pressure to asecond pressure below the first pressure while the thermoplasticpolymeric members remain softened to at least partially foam thethermoplastic polymeric structural members.
 2. A method according toclaim 1, further comprising d) heating the at least partially foamed,thermoplastic polymeric members to a second temperature below atemperature at which the structure collapses to soften the thermoplasticpolymeric members and infusing the softened thermoplastic polymericmembers with a second at least one inert gas at a third pressure that issufficient to cause the second at least one inert gas to permeate intothe softened thermoplastic polymeric members; and e) reducing thepressure to a fourth pressure below the third pressure while thethermoplastic polymeric members are softened and at a temperature belowa temperature at which the structure would collapse to further foam thethermoplastic polymeric members.
 3. A method according to claim 1,wherein the second pressure is atmospheric pressure.
 4. A methodaccording to claim 1, wherein the article includes a structural portionother than the thermoplastic polymeric members.
 5. A method according toclaim 1, wherein before b) each opening has at least one dimension thatis greater than at least one dimension of at least one adjacent unfoamedthermoplastic polymeric member.
 6. A method according to claim 1,wherein the pattern repeats in two directions perpendicular to oneanother.
 7. A method according to claim 1, wherein the pattern has atleast three repeating units in sequence in at least one direction.
 8. Amethod according to claim 1, wherein the structure comprises elongatedopenings.
 9. A method according to claim 1, wherein of openings definedby the interconnected, unfoamed, thermoplastic polymeric members of a)each has as at least one dimension that is from about 1 mm to about 10mm.
 10. A method according to claim 1, wherein the foamed article is acomponent for an article of footwear.
 11. A method according to claim 1,wherein during the step c) foaming the structure is constrained in atleast one but less than all directions.
 12. A method according to claim1, wherein the thermoplastic polymeric members are arranged in a latticepattern.
 13. A method according to claim 7, wherein the repeating unitsare uniform.
 14. A method according to claim 1, wherein an outer surfaceof the foamed article comprises a plurality of openings.
 15. A methodaccording to claim 1, wherein the thermoplastic polymeric members have across-sectional shape that is circular, oval, square, or rectangular.